Flame retardant polyesters containing polyamides and phosphine oxides

ABSTRACT

FLAME RETARDED POLYESTER CONTAINING A FLAME RETARDING AMOUNT OF A THERMALLY STABLE NITROGEN CONTAINING POLYMERIC FLAME RETARDANT AND A FLAME RETARDING AMOUNT OF A THERMALLY STABLE PHOSPHINE OXIDE FLAME RETARDANT, THE COMBINED FLAME RETARDANT EFFECT OF SAID FLAME RETARDANTS BEING SYNERGISTIC.

United States Patent 3,629,365 FLAME RETARDANT POLYESTERS CONTAINING POLYAMIDES AND PHOSPHINE OXIDES James H. Gardner, Enka, N.C., assignor to Altzona Incorporated, Enka, N.C. No Drawing. Filed Sept. 14, 1970, Ser. No. 72,225 Int. Cl. (308g 41/04 US. Cl. 260857 PE 12 Claims ABSTRACT OF THE DISCLOSURE Flame retarded polyester containing a flame retarding amount of a thermally stable nitrogen containing polymeric flame retardant and a flame retarding amount of a thermally stable phosphine oxide flame retardant, the combined flame retardant effect of said flame retardants being synergistic.

SUMMARY OF THE INVENTION The present invention is directed to the preparation of a flame retarded polyester which, in addition to being flame retardant, reflects fully acceptable processing characteristics required for the production of, for example, acceptable staple and filamentary yarn for both textile and carpet end uses. The addition of thermally stable flame retardant is accomplished by routine procedure and unexpectedly demonstrates a synergistic flame retardant effect through a full denier range in, for example, fabric and carpet such as level loop and shag carpet made from filamentary yarn which is readily processable in the trade. The flame retardant additive components, in addition to being thermally stable, are chemically stable throughout use as herein described and claimed. Polyester staple, filament, yarn, film, and sheets thereof can be flame retarded in the practice of this invention.

DETAILED DESCRIPTION Polyester polymer and copolyesters, as more fully described herein, are made flame retardant by incorporating therein the defined two-component flame retardant additive prior to spinning. The phosphine oxide flame retardant additive component can be added during polymerization at transesterification, or it can be mixed into polyester polymer shortly before spinning. If added during polymerization, said phosphine oxide additive can become a repeating unit in the polymer backbone and can be modified, prior to said addition, for example, to enhance dyeability of the resulting flame retardant polymer. Typical phosphine oxides that can be so utilized and their preparation are set forth, for example, in the Sept. 20, 1952, article by Paul W. Morgan and Barbara C. Herr, volume 74, pages 4526 to 4529 found in Journal American Chemical Society 1952. Preferred phosphine oxide additives include triphenyl phosphine oxide, trioctyl phosphine oxide, and bis-(p-carbomethoxyphenyl) phenyl phosphine oxide.

The thermally stable nitrogen containing polymeric flame retardant additive is preferably incorporated into the polymer melt prior to spinning, after polymerization and, together with the phosphine oxide flame retardant, reflects a synergistic flame retardant effect in the resulting spun filaments. Preferred chemically and thermally stable nitrogen containing polymeric flame retardant additives include nylon 6 and nylon 66. Copolyamides as described in US. Pat. No. 3,492,368 can also be utilized. The required performance of any such selected polymer as to stability and polyester flame retardant effect per se can be routinely determined with a minimum of experimentation.

The flame retarded polyester or copolyester produced ice in accordance with this invention can be satisfactorily processed in the trade and, for example, successfully deep dyed by conventional dyeing procedures from an aqueous system without the use of a carrier or with the use of a lesser amount of carrier. The variety of polyester, dyes, or mixtures thereof that can be utilized is wide in scope and depends on processing conditions and desired end results, all within the realm of routine experimentation.

In the practice of the present invention, conventional additives can be incorporated prior to spinning to achieve a desired result; such additives include pigments, dyes, antioxidants, delustrants, etc., singularly or in combination.

The flame retardant additive components of the present invention will be preferably incorporated by mixing immediately prior to extrusion or spinning. This control enables the avoidance of the problem resulting when certain such additives, introduced during polymerization, would normally adversely affect the processing of and/or degrade the resulting polymer.

As stated heretofore, however, the phosphine oxide additive can be incorporated during polymerization and can also become part of the polymer backbone without degrading the resulting polymer.

Although the particular mechanism and reason for the synergistic effect of the flame retardant composition utilized in accordance with the present invention is not fully understood, it is considered that the results positively speak for themselves and represent a significant contribution to the art in providing, for example, synthetic organic polyester filaments that can be readily processed, which filaments are flame retarded and can be subsequently handled without the skill of the art to produce desired dyed fabrics and carpeting. These end use products are flame retardant as more specifically herein described. Staple, film, and sheets of flame retarded polyester can be produced.

The polyesters employed in practicing this invention include those which are well-known in the art as exemplified by US. Pats. 2,465,319; 2,901,466; 2,744,089; and 3,018,- 262. It is to be understood that the term polyester includes both homopolyesters and copolyesters.

In incorporating the flame retardant additive compo nents into the polymer melt immediately prior to spinning, known means which will achieve a thorough mixing can be utilized. It is essential that moisture be reduced to an absolute minimum in the polymer, the additives, and the apparatus involved. The latter can be accomplished, for example, by heating the polymer and additives separately or at a temperature below the melting point of any one of the components. The time required for effective drying to reduce moisture content can, of course, be routinely determined. Mechanical mixing will normally be utilized followed by spinning to produce flame retarded commcr-. cially acceptable filaments. Flame retardant polymeric films or sheets can also be produced.

Typical polyesters which can be modified in the practice of the present invention include those set forth in US. Pats. 2,465,319; 2,437,232; 2,739,957; and 2,895,946. Various processes which can be utilized to prepare such polyesters are set forth, for example, in US. Pats. 3,433,770 and 3,406,152 the latter patent also disclosing the addition of additives to control pilling.

Copolyester can be prepared from terephthalic acid or an ester forming derivative thereof and a glycol of the formula HO(CH ),,OH, wherein n is an integer of from 2 to about 10, in the presence of a dye sensitizing sulfonate containing compound, a branching agent, such as glycerol, and a dye dispersing and dye retaining aliphatic diacid or ester thereof. The particular copolyester, sulfonate containing additive, branching agent and aliphatic diacid (or ester thereof) selected singularly or in combination is not critical.

Polyesters and copolyesters which can be modified in the practice of this invention are well-known in the art and include those of US. Pat. 3,018,272; this disclosure also sets forth sulfonate group containing compounds which can be utilized in the practice of the present invention. US. Pat. 3,096,358 sets forth additional sulfonate compounds which can be utilized in conjunction with a selected aliphatic diacid of the formula HOOC(CH),,COOH

11 having a value of from 2 to 18. Preferred species aliphatic diacid additives are the azelate and adipate diacids and ester derivatives thereof.

Branching agents which can be utilized include hexametreol; pentaerythritol; trirnethylolpropane; sorbitol; trimethylol ethane; glycerol; trimethylol benzene-1,3,5; tripropylol benzene-1,3,5; tributylol benzene-1,3,5; trihexylol benzene-1,2,6; trimethyl trimesate; triethyl trimesate; tripropyl trimesate; tetrarnethyl pyromellitate; tetrarnethyl mellophanate; trimethyl hemimellitate; trimethyl trimellitate and tetrarnethyl prehnitate.

Examples of sulfonate group containing compounds which can be utilized include metallic salts of sulfomonocarboxylic esters, sulfodicarboxylic esters, monohydric and dihydricalcohols containing at least one sulfonic acid group, and monohydric alcohols containing one carboxylic ester group and at least one sulfonic acid group.

Among the basic and disperse dyestuffs which readily dye the fibers produced from the flame retarded polyester of this invention are the Genacryl and Celliton dyes discussed on pages 432 to 433 of the American Dyestufi Reporter, volume 43, 1954, for example, Genacryl Red 63 (a basic dye of quaternary ammonium type), Genacryl Pink G. (Basic Red 13; Color Index No. 48015), Genacryl Blue 6G; Celliton Fast Red GGA Ex. Cone (Disperse Red 17; Color Index No. 11210); Celliton Fast Blue AF Ex. Cone (Color Index No. 61115); Fuchsine SBP (a basic dye of the triphenylmethane type); Fuchsine Conc. Basic Violet 14 (Color Index No. 12510); Methyl Violet 2B; Brilliant Blue 6G; Methylene Blue SP; Victoria Green WB (Color Index 657); Victoria Green (Basic Green 4; Color Index No. 42000); Rhodamine B (Color Index 749); Brilliant Green B (Color Index 662); Sevron Brilliant Red 46; Maxilon Red BL; Basacryl Blue GL; and the like.

Additional specific dyestuffs which can be utilized include the following:

Dyestuff: Color Index Name tSevron Yellow R Basic Yellow 11. Astrazon Yellow 7GLL Basic Yellow 21. lSevron Orange G Basic Orange 21. Maxilon Red BL Basic Red 22. Astrazon Red BBL Basic Red 23. Astrazon Red RL Basic Red 25. Sevron Red GL Basic Red 18. Sevron Blue ER Basic Blue. Sevron Blue G Basic Blue 4. Sevron Blue BGL Basic Blue 35. Sevron Blue NF Basic Blue. Resolin Blue FBLD Disperse Blue 56. Sevron Brilliant Red D Basic Red 19.

The phosphine oxide flame retardant additive has the following generic formula:

wherein R, R and R" are aromatic, aliphatic, or substituted aliphatic radicals which can be esterified. Aromatic radicals include phenyl and substituted phenyl and esters thereof such as carbomethoxy substituted phenyl. When R, R. or R" are individually aliphatic, it can be alkyl radical, for example of from 1 to 18 carbon atoms. From about 1 mol percent to about 10 mol percent phosphine oxide can be utilized.

The stable nitrogen containing polymeric flame retarding component can be, for example, nylon 6, nylon 66, copolyamides, and other nitrogen containing polymers which can be processed under normal polyester processing conditions and which function to impart flame retardancy to polyester polymers in accordance with this invention. Any such flame retardant effect, of course, can be routinely determined with a minimum of experimentation.

The representative examples and comparative data which follow clearly demonstrate the practical utility of applicants invention. It is understood, however, that for the flame retarded synthetic organic filaments produced in the practice of the present invention to be acceptable, said filaments must be processa'ble to fabric and/or carpeting and compatible with appropriate treating procedures and compositions such as dyeing, anti-soiling and anti-static compositions, said processing compositions utilized being ones which do not, but minutely if at all, reduce flame retardancy.

The selection of specific dyes, carriers, and dyeing procedures, for example, will vary in the trade and it is to be understood that some routine experimentation may be required to maintain the built-in flame retardancy of the synthetic polymers disclosed in this specification; such experimentation, however, would be routine in nature and well within the skill of the art and trade.

The following examples are representative and illustrate the significant utility and novelty of the present in vention. The embodiments which follow are preferred and illustrate the herein described and claimed invention but are not to be construed as limiting the scope thereof.

EXAMPLE I This example illustrates the preparation of a polyester shag greige good yarn and shag carpet produced from said yarn.

Conventional polyester polymer chips were dried at 125 C. to a moisture content below about 0.21%.

Conventionally prepared nylon 6 chips were dried under vacuum at C. to a moisture content less than 0.25%. Triphenyl phosphine oxide powder was dried at C. under vacuum to a moisture content less than 0.25

The dried polyester chips, while remaining in the dryer, were cooled to about 48 C.; 5 mol percent dried nylon chips and 5 mol percent triphenyl phosphine oxide powder were then mechanically mixed together; this mixture was added to the dried polyester chips and then tumbled for one hour at 48 C. The resulting mixture was transferred to a hopper positioned over an extruder and then melt spun under normal polyester melt spinning condi trons at a spin temperature of 295 C. The polyester chip polymer had an I.V. of 89, a moisture content of .003 and was spun into 68 filaments, 1200 denier yarn having a yarn I.V. of .73 and finish retention of 1.3%.

After spinning, the resulting filaments were conventionally drawn at a draw ratio of 4.62, followed by bulking and routine takeup onto a package. This drawn yarn had a tenacity (g.p.d.) of 4.10, a percent elongation of 17.2, and a modulus of elasticity (5%) of 69.7. The packaged yarn was then routinely processed into a 26- ounce shag carpet with plain jute backing by single end twisting said yarn at 3.0 Z; it was then two plied at 3.0 S to give a balanced yarn, wound onto one-pound skeins, steam tumbled at F. for 20 minutes, and then autoclaved at 290 F. The yarn was then wound onto packages, creeled and tufted with needle gauge shag tufting machine using six stitches per inch with a 1% stroke. Each tuft line was /8" apart and 24 needles were on each 9" needle bar; 30" width jute backing was tufted to a 26-ounce face weight shag.

Eight samples of this shag carpeting were then sub jected to flammability testing. The procedure utilized was that for testing for carpet flammability as outlined in the US. Department of Commerce Standard Procedure DOC FF 1-70 (pill test) with the exception of the following two modifications: (1) the carpet samples were dried in a gravity convection oven instead of a forced circulation type, and (2) the carpet samples were dried over calcium chloride instead of silica gel. Other than these two modifications, the test procedure was fully complied with. All eight samples successfully passed this pill test.

The particular backing option selected for carpet will vary and includes, in addition to plain jute, normal latex and flame retarded latex. Combinations thereof in a double backed carpet can also be used.

In general, disperse dyes are utilized in the trade to effectively deep dye normal polyester, whereas basic dyes are preferred for dyeing modified polyester such as cationic dyeable polyester.

When an optional carrier is to be considered, the biphenyl type will be evaluated for carpet dyeing, and, for textiles, carriers such as ortho phenyl, phenol and chlorobenzene will be considered.

It was surprising that the flame retarded polyester of this invention could be effectively deep dyed without the use of a carrier. Alternatively, a lesser amount of a selected carrier can be utilized to achieve an additional deep result without adversely affecting the polyester flame retardant properties.

EXAMPLE II A simple comparative flammability test consisting of taking several filaments spun from conventionally prepared polyester polymer, twisting them together and bringing them into contact with a burning match was conducted. The twisted filaments were either highly flammable, selfextinguishing or would not ignite. The following data was obtained:

(A) Polyester polymeric filaments without any flame retardant additive were highly flammable and completely burned.

(B) Polyester polymeric filaments with 4 mol percent nylon 6 flames retardant additive were slighly flame retardant, i.e., self-extinguishing in 10 to seconds after removal of the burning match.

(C) Polyester polymeric filaments with 4 mol percent triphenyl phosphine oxide flame retardant additive were self-extinguishing in 1 to 15 seconds after removal of the burning match.

(D) Polyester polymeric filaments with 4 mol percent trioctyl phosphine oxide flame retardant additive were self-extinguishing in 10 to 15 seconds after removal of the burning match.

(E) Polyester polymeric filaments with 4 mol percent nylon 6 and 4 mol percent triphenyl phosphine oxide would not ignite when held in the flame of a burning match.

EXAMPLE III Shag carpet samples of the flame retarded invention polyester prepared as set forth in Example I above were deep dyed by conventional procedures from an aqueous system, without carrier, and utilizing a normal latex backing.

The following Beck dyeing procedure was applied to these polyester carpet samples. I

All chemical and dye percentages are based on the weight of the carpet and the bath ratio for dyeing and rinsing is 40:1. A cold 40:1 bath is set with 3% of 28% acetic acid and 1% monosodium phosphate.

The carpet was run five minutes cold before adding the predissolved disperse dyestuffs. The dyes used were: 0.14% Resolin Blue FBLD (Disperse Blue 71); 0.175% Celliton Fast Pink RF (Disperse Red 4); and 0.455% Latyl Yellow 3G powder (Disperse Yellow 54). The carpet was run an additional ten minutes cold to allow thorough distribution of the dyestuff. The bath was heated to 70 C. over 15 minutes and run for ten minutes at 70 C. The pH of the bath was checked and adjusted to 4.5 5.5 with acetic acid. The bath was heated to the boil at 1 C. per minute and then dyed for 45 minutes at the boil. The carpet was sampled for shade. The bath was then cooled (1 C. per minute) to 70 C. before dropping the bath.

The carpet was then rinsed in a fresh bath for ten minutes at 50 C. and then scoured at 70 C. with 2% soda ash. The carpet was rinsed again for ten minutes at 50 C and ten minutes cold. The carpet was then removed, extracted and dried in the normal manner.

The deep dyed polyester carpet of this example was prepared without carrier and represents a significant result, as it is well-known in the art that normal polyester will not effectively deep dye without the use of a carrier.

The dyed shag carpet samples of this example, in addition to passing the DOC carpet flammability test as herein described, passed the conventional tests for crocking and Wash-fastness and reflected acceptable light-fastness properties.

It is understood that the preceding representative examples can be varied within the scope of this total specification disclosure as it would be understood and practiced by one skilled in the art with a minimum of routine experimentation.

What is claimed is:

'1. Flame retarded polyester containing (1) from about 1 mole percent to about 10 mole percent of thermally stable linear fiber-forming polyamide flame retardant, and (2) from about 1 mole percent to about 10 mole percent of thermally stable phosphine oxide flame retardant having the formula:

0 Ri -R t.

wherein R, R and R" are aromatic, aliphatic or substituted aliphatic radicals and esters thereof, the combined flame retardant eifect of said flame retardants (1) and (2) being synergistic.

2. Flame retarded polyester according to claim 1 wherein said phosphine oxide is triphenyl phosphine oxide.

3. Flame retarded polyester according to claim 1 wherein said phosphine oxide is triphenyl phosphine oxide and said polyamide is nylon 6.

4. Flame retardad polyester accordng to claim 1 wherein said phosphine oxide is trioctyl phosphine oxide.

5. Flame retarded polyester according to claim 1 wherein said phosphine oxide isbis-(p-carbomethoxy phenyl) phenyl phosphine oxide.

6. Flame retarded polyester according to claim 1 wherein said polyamide is nylon 6 and said phosphine oxide is bis- (p-carbomethoxy phenyl) methyl phosphine oxide.

7. A flame retarded polyester filament containing (1) from about 1 mole percent to about 10 mole percent of linear fiber-forming polyamide flame retardant and (2) from 1 mole percent to about 10 mole percent of phosphine oxide flame retardant, said phosphine oxide having the formula:

0 Ri R BL wherein 'R, R and R are aromatic, aliphatic or substituted aliphatic radicals and esters thereof, the combined flame retardant effect of said flame retardants (1) and (2) being synergistic.

8. Flame retarded polyestef filament according to claim 7 wherein said phosphine oxide is triphenyl phosphine oxide.

9. Flame retarded polyester filament according to claim 7 wherein said phosphine oxide is triphenyl phosphine oxide and said polyamide is nylon 6-.

10. Flame retarded polyester filament according to claim 7 wherein said phosphine oxide is trioctyl phosphine oxide and said polyamide is nylon 6.

11. Flame retarded polyester filament according to claim 7 wherein said polyamide' is nylon 6 and said phosphine oxide is bis-(p-carbomethoxy phenyl) phenyl phosphine oxide.

12. Flame retarded polyester filament according to claim 7 wherein said polyamide is nylon 6 and said phosphine oxide is bis- (p-carbomethoxy phenyl) methyl phosphine oxide.

References Cited UNITED STATES PATENTS PAUL LIEBERMAN, Primary Examiner US. Cl. X.R. 

